1. Field of the Invention
The present invention relates to a symmetric hyperbranched silicone-modified polymerizable compound having a siloxane chain, a modularized manufacturing method of the polymerizable compound, and a silicone-modified composition using the polymerizable compound.
2. Description of the Related Art
It has been disclosed that a molecule (carbodendrimer) containing a siloxane structure having regularly branched structures has low viscosity as compared with the conventional linear siloxane having the same number of the silicon atoms, and gives an excellent material as mold releasing agent, lubricant, resin modifier or cross-linking agent (Patent Document 1). Further, a siloxane dendrimer of a polymerizable compound in which a branched siloxane utilizing its features is grafted has been developed (Patent Document 2). However, the siloxane having such a structure has short branched chains and is chemical structurally brittle, so that it is poor in flexibility as a dendrimer. Also, effects of steric hindrance appears accompanied by becoming the grafted branched chain large (generation increases), and reactivity of the polymerizable functional group becomes insufficient, so that commercialization has not been done in the third generation in which the branch is three units in one side chain.
Due to the problems as mentioned above, it has been developed a method in which a siloxane chain is tried to introduce into an allyl ether compound (CH2═CHCH2OR) by hydrosilylation, but it has been known that among the olefins of the allyl ether compound, 10 to 20% thereof is internally rearranged to form a 1-propenyl ether product (CH3CH═CHOR), which is a main by-product. Further, it has also been known when the above 1-propenyl ether is hydrolyzed by moisture, etc., in the air, propion aldehyde is generated, which causes bad smell in the final product, etc. To solve the above-mentioned problem of the bad smell, it has been disclosed a method in which a vinyl ether group in the 1-propenyl ether is reduced to propyl ether (CH3CH2CH2OR) by hydrogenation reaction using a hydrogen gas under pressure in an autoclave, whereby chemical decomposition thereof is prevented to avoid occurrence of the bad smell (Patent Document 3). Further, there is a problem that the decomposed aldehyde and alcohol are reacted to form acetal in some cases, and the acetal is not reacted by the hydrogenation reaction but gradually decomposes by moisture or acid, which continues to emit the bad smell from the product. To solve the above problem, it has been disclosed a method in which a solid acid is used at the hydrogenation reaction, which can prevent from generating a substance which emits the bad smell (Patent Document 4), and a method in which the generated propion aldehyde is acetalized (CH3CH2CH(OR′)2) by lower alcohol (R′OH) to make the compound which emits the bad smell a compound having a low boiling point, which is removed by distillation (Patent Document 5). However, these methods are measures for the purposes of suppressing occurrence of the bad smell component or removing the same, whereby they are not the method that basically suppresses the occurrence of the internally rearranged product at the time of the reaction.
On the other hand, it has been known that it is possible to reduce an amount of an internally rearranged product of olefin by using β-methallyl alcohol which is 2-methyl-2-propen-1-ol at the time of the hydrosilylation reaction. However, there are problems that isobutyl aldehyde formed with a minute amount emits an unpleasant odor, and the β-methallyl alcohol used as a raw material is significantly expensive as compared with the allyl alcohol.
Therefore, a branched type siloxane with good purity can be difficulty synthesized from a branched compound containing an ether bond having flexibility due to the problem of the above-mentioned internal rearrangement, and when a silicone is tried to introduce into a branched compound having allyl groups, if internal rearrangement of a by-product is generated in the hydrosilylation reaction, a product one of which is symmetric to the silicone chain cannot be obtained. When an attempt is made to apply the product to use for pharmaceuticals, medical devices or foods, an asymmetric branched compound markedly affected on the effectiveness of the physiological activity due to the formation of diastereomers. Further, it has been known that it is extremely difficult in synthetic chemistry to introduce a branched structure which is positionally and sterically pure and symmetric.